This invention relates to a method of preparing stable amino acid chelates. Moreover, this invention relates to a stable new form of amino acid chelates and to the new chelate prepared by the process.
Certain metal ions are known to be beneficial in stimulating plant growth and in the production of larger, stronger plants, increased production of fruits or vegetables or the generation of more flavorful produce. Other benefits have been observed when these metals are added to the diet of animals and humans.
It has become generally accepted that the chelated forms of these metals with amino acids are demonstrably better assimilated by plants, animals, and human beings than metal salts, the plant, animal and human tissues showing increased metal content when exposed to metal amino acid chelates. Prior art metal amino acid chelates are formed by reacting metal salts with amino acids. For example, metal salts, such as salts of iron, zinc, copper, magnesium, cobalt or calcium, when reacted with an amino acid, for example glycine, would form ferrous glycinate, zinc glycinate, copper glycinate, magnesium glycinate, cobalt glycinate, cobalt glycinate, or calcium glycinate. However, the metal amino acid chelates made according to the prior art processes result in products that are insoluble or unstable in water, particularly at a low pH or a pH above 7. The chelation process shown in certain prior art references requires heating under nitrogen (U.S. Pat. Nos. 2,877,253 and 2,957,806). Other prior art techniques produce chelates which are unstable or precipitate at a pH above 8 (U.S. Pat. Nos. 4,216,143 and 4,216,144). Additionally, these prior art chelates have been known to precipitate out of solution when other chemical compounds, such as phosphates, are added to the chelate solution.
Prior art chelates also show stability problems over a period of time, the compounds precipitating after two or three days (U.S. Pat. No. 4,216,144). U.S. Pat. No. 3,396,104 shows formation of insoluble metal proteinates using saline water.
Therefore, there is a real need for a material capable of delivering high levels of desirable metal ions to plants, animals or human beings. The utility of such a material would be further enhanced if it is soluble in both acid, neutral and basic aqueous solutions, particularly if the materials remain in solution even after the addition of other soluble materials.